SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78dd712a4eb4fd4fbef07e3078623e7bdabd22ad1816e096091ecd2678b9ff20' 
  AND token = 'TXmG1vSlpRV0SbvGMutVHJ51qTNtz91GEDr355V+yOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}